The formation of insoluble, ubiquitin-containing aggregates of cytoskeletal proteins appears to be important in the pathogenesis of (AD). Qualititative and quantitative immunochemical methods will be used to investigate the role of ubiquitin in this process. Using a panel of antibodies to cytoskeletal proteins and ubiquitin, cytoskeletal and microtubule preparations will be examined for relatively stable specific ubiquitin-conjugated cytoskeletal proteins, the presence of which have been suggested by preliminary studies by Dr. Black. These materials will be characterized further by 2-D gel electrophoresis after antibody affinity chromatography. Quantitative assays will be developed to measure ubiquitin, ubiquitin conjugates, and tau proteins in autopsy brain samples, using ELISAs, dot blots and immunoblots. Quantitative comparisons of these antigens will be made between Alzheimer and control brain, and between affected and unaffected regions of Alzheimer brain. These experiments will test the hypothesis that the interaction of ubiquitin with cytoskeletal proteins is altered in Alzheimer's disease. Quantitative immunochemical methods, including 35S-methionine labeling will then be used to examine the effect of oxidative and other stresses (including heat shock) on the expression of the above antigens in Alzheimer and control fibroblasts. These experiments will test the hypothesis that metabolic stress may have a role in the pathogenesis of the pathological lesions in AD.